How is testing for mold done?

In the United States, the identification of mold requires clinical laboratory testing. This is because there are no national standards for defining what a “mold” is, nor any nationally accepted method to objectively identify mold species that must be included in an air sample or surface/soil sample analyzed for fungi.

The analytical chemistry of building-associated fungal species in air and dust samples is complex. It involves a series of steps: sampling, isolation, culturing (to grow sufficient amounts), and characterization of the species present. The characterization process can take many weeks or even months to complete based on how much time is required for growth and observation under phase-contrast microscopy (PCM).

Some companies offer mold testing, but they are not clinical laboratories. They contract with commercial analytical laboratories to conduct the required tests.

The most common fungal spores found indoors are Cladosporium sphaerospermum and Penicillium chrysogenum (also called Penicillium notatum). These two molds are responsible for about 80% of all the fungi found in indoor air samples. Other species include Aspergillus Versicolor, Chaetomium globosum, Chaetomium strumarium, Epicoccum nigrum, Fusarium oxysporum, Helminthosporium solani, Mucor racemosus, Stachybotrys chartarum, Trichoderma viride, Trichophyton rubrum, and Ulocladium chartarum.

In the U.S., the coalition of laboratory analysts in private practice specializing in mycology consulting for building-related complaints stresses that a specifically designed environmental protocol is required to address these types of complaints that can be very difficult to solve or correct. These experts also think that a qualified mycologist should only do mold testing with proper training and experience in clinical laboratory methods. This group does not recommend using non-specific color tests, tape lifts, “scopes,” or air samples collected with unproven sampling devices because such results cannot be used for a conclusive diagnosis. Although some types of the model, such as settled dust or air samples, may be collected, these require specific isolation and culturing methods under environmental conditions of 22 degrees C and 30% to 60% relative humidity.

Clinical laboratory analysis is the only way mold species can be identified with any degree of certainty…without this testing, no identification process meets any recognized level of scientific scrutiny. There are no accepted “standardized” procedures for collecting or culturing air or surface samples. We have many new tools available to use today, but unfortunately, some are still just being developed.”

– EPA publication collection abstracts on “Mold Remediation in Schools and Commercial Buildings.”

Testing for Stachybotrys chartarum (Stachybotrys atra) should include analysis of spores and mycotoxins in air samples. Stachybotrys chartarum is the most toxic indoor fungi. Still, it usually appears as black or dark green spots on wallboard surfaces rather than as typical molds growing on walls or ceilings. Most Stachybotrys species are very slow growers that require high moisture levels to thrive.